I think this must be the neon maths symbols someone
mentioned too:
http://www.arts-project.org/aol/pics/scr-0.3.1-3.jpg
No it's not aRts or mbox (although John Dunn's SoftStep looks like it's along
similar lines:
http://www.algoart.com/web/softstep.htm)
Still looking - but I'm starting to think it must have been a dream. :)
Dave